Using safeStateClone within doPurge to applyIntermediateTarget after
successful volume purge has led to various type deficiencies being revealed
in common.js. Add several inline types in common.js to satisfy
the type checker (credit: Page <page@balena.io>). Delete common.d.ts
since it's not required and might mistakenly mask true I/O types of
functions in common.js.
Closes: #1611
Change-type: patch
Signed-off-by: Christina Wang <christina@balena.io>